Relative risk of irritable bowel syndrome following acute gastroenteritis and associated risk factors.

SUMMARY: A prospective cohort study using electronic medical records was undertaken to estimate the relative risk (RR) of irritable bowel syndrome (IBS) following acute gastroenteritis (GE) in primary-care patients in The Netherlands and explore risk factors. Patients aged 18-70 years who consulted for GE symptoms from 1998 to 2009, met inclusion/exclusion criteria and had at least 1 year of follow-up data were included. Patients with non-GE consultations, matched by age, gender, consulting practice and time of visit, served as the reference group. At 1 year, 1·2% of GE patients (N = 2428) had been diagnosed with IBS compared to 0·3% of the reference group (N = 2354). GE patients had increased risk of IBS [RR 4·85, 95% confidence interval (CI) 2·02-11·63]. For GE patients, concomitant cramps and history of psycho-social consultations were significantly associated with increased risk. GE patients had increased risk of IBS up to 5 years post-exposure (RR 5·40, 95% CI 2·60-11·24), suggesting there may be other contributing factors.

Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort.

BACKGROUND: We investigated associations of known breast cancer risk factors with breast density, a well-established and very strong predictor of breast cancer risk. METHODS: This nested case-control study included breast cancer-free women, 265 with high and 860 with low breast density. Women were required to be 40-80 years old and should have a body mass index (BMI) <35 at the time of the index mammogram. Information on covariates was obtained from annual questionnaires. RESULTS: In the overall analysis, breast density was inversely associated with BMI at mammogram (P for trend<0.001), and parity (P for trend=0.02) and positively associated with alcohol consumption (ever vs never: odds ratio 2.0, 95% confidence interval 1.4-2.8). Alcohol consumption was positively associated with density, and the association was stronger in women with a family history of breast cancer (P<0.001) and in women with hormone replacement therapy (HRT) history (P<0.001). Parity was inversely associated with density in all subsets, except premenopausal women and women without a family history. The association of parity with density was stronger in women with HRT history (P<0.001). CONCLUSION: The associations of alcohol and parity with breast density appear to be in reverse direction, but stronger in women with a family history of breast cancer and women who ever used HRT.

Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model.

Diagnosis of the ischemic power of epicardial stenosis with concomitant microvascular disease (MVD) is challenging during coronary interventions, especially under variable hemodynamic factors like heart rate (HR). The goal of this study is to assess the influence of variable HR and percent area stenosis (%AS) in the presence of MVD on pressure drop coefficient (CDP; ratio of transstenotic pressure drop to the distal dynamic pressure) and lesion flow coefficient (LFC; ratio of %AS to the CDP at the throat region). We hypothesize that CDP and LFC are independent of HR. %AS and MVD were created using angioplasty balloons and 90-µm microspheres, respectively. Simultaneous measurements of pressure drop (DP) and velocity were done in 11 Yorkshire pigs. Fractional flow reserve (FFR), CDP, and LFC were calculated for the groups HR < 120 and HR > 120 beats/min, %AS < 50 and %AS > 50, and additionally for DP < 14 and DP > 14 mmHg, and analyzed using regression and ANOVA analysis. Regression analysis showed independence between HR and the FFR, CDP, and LFC while it showed dependence between %AS and the FFR, CDP, and LFC. In the ANOVA analysis, for the HR < 120 beats/min and HR > 120 beats/min groups, the values of FFR (0.82 ± 0.02 and 0.82 ± 0.02), CDP (83.15 ± 26.19 and 98.62 ± 26.04), and LFC (0.16 ± 0.03 and 0.15 ± 0.03) were not significantly different (P > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02 and 0.75 ± 0.02), CDP (35.97 ± 25.79.10 and 143.80 ± 25.41), and LFC (0.09 ± 0.03 and 0.22 ± 0.03) were significantly different (P < 0.05). A similar trend was observed between the DP groups. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR, while they can significantly distinguish %AS and DP groups.

Use of (1-3)-beta-d-glucan concentrations in dust as a surrogate method for estimating specific fungal exposures.

UNLABELLED: Indoor exposure to fungi has been associated with respiratory symptoms,often attributed to their cell wall component, (1-3)-beta-D-glucan. Performing(1-3)-beta-D-glucan analysis is less time consuming and labor intensive than cultivation or microscopic counting of fungal spores. This has prompted many to use(1-3)-beta-D-glucan as a surrogate for fungal exposure. The aim of this study was to examine which indoor fungal species are major contributors to the (1-3)-beta-D-glucan concentration in field dust samples. We used the quantitative polymerase chain reaction (QPCR) method to analyze 36 indoor fungal species in 297 indoor dust samples. These samples were also simultaneously analyzed for (1-3)-beta-D-glucan concentration using the endpoint chromogenic Limulus Amebocyte lysate assay. Linear regression analysis, followed by factor analysis and structural equation modeling, were utilized in order to identify fungal species that mostly contribute to the (1-3)-beta-D-glucan concentration in field dust samples. The study revealed that Cladosporium and Aspergillus genera, as well as Epicoccum nigrum, Penicillium brevicompactum and Wallemia sebi were the most important contributors to the (1-3)-beta-D-glucan content of these home dust samples. The species that contributed most to the (1-3)-beta-D-glucan concentration were also the most prevalent in indoor environments. However, Alternaria alternata, a common fungal species in indoor dust, did not seem to be a significant source of (1-3)-beta-D-glucan. PRACTICAL IMPLICATIONS: This study revealed that the (1-3)-beta-D-glucan content of different fungal species varies widely. (1-3)-beta-D-glucan inhouse dust from the Greater Cincinnati area may be a good marker for some fungal species of the Cladosporium and Aspergillus genera. In contrast, Alternaria alternata did not contribute much to the (1-3)-beta-D-glucan load. Therefore, (1-3)-beta-D-glucan concentration in field samples as a surrogate for total fungal exposure should be used with caution.

Gender-specific predictors of genital herpes vaccine acceptance in a college population.

Vaccines represent one promising method for reducing the sexually transmitted disease (STD) epidemic. This study evaluated whether influences on the decision to accept a genital herpes vaccine differed by gender. In all, 518 college students completed a questionnaire on sexual history, health beliefs, and acceptance of a potential genital herpes vaccine. Each predictor variable plus a gender interaction term were analysed in separate logistic regression models. Follow-up analyses were performed by gender for outcomes that displayed significant interactions. Results indicated that a prior history of an STD and increased perception of risk for acquiring genital herpes were significant predictors of vaccine acceptance for men, while younger age and concerns about vaccine safety were significant predictors for women. Endorsement of a vaccine strategy targeting sexually experienced people was an influential factor for both genders, but was a much stronger one for women. Results suggest that gender-specific strategies may be crucial to genital herpes vaccine acceptance.

Body weight alterations under early corticosteroid withdrawal and chronic corticosteroid therapy with modern immunosuppression.

UNLABELLED: Weight gain is a well-known complication of corticosteroid maintenance therapy. The purpose of our study was to compare patterns of weight gain under chronic corticosteroid therapy (CCST) to those observed under early corticosteroid withdrawal (CSWD) in renal transplant recipients. METHODS: Renal transplant recipients who underwent early CSWD in IRB-approved prospective trials were compared to a historical control group of patients receiving CCST who were matched for age, sex, and race. RESULTS: One hundred sixty-nine patients with early CSWD were compared to 132 patients who received CCST. Mean population weight gain was significantly higher in CCST patients at 12 months (5.52 kg vs 3.05 kg, P < .05) posttransplant. Caucasian CSWD patients demonstrated a greater reduction in weight gain with CSWD than African Americans (mean weight decrease 2.9 vs 1.9 kg/patient, P < .05). Patients who were overweight (body mass index [BMI] 25-30) or obese (BMI > 30) demonstrated a greater reduction in weight gain with CSWD at 1 year (mean reduction in weight gain with CSWD 5.3 kg/patient and 4.4 kg/patient) than did patients of normal weight (BMI < 25; 0.1 kg/patient, P < .01 and <.05 versus BMI < 25). CONCLUSIONS: Early CSWD patients gain significantly less weight than CCST patients following transplantation. Marked variations in the effect of early CSWD on weight gain may be observed due to race and pretransplant BMI. Caucasians and overweight patients demonstrate greater benefits from CSWD than African Americans and patients with normal BMI.

Outcomes of patients with rejection post-polyomavirus nephropathy.

INTRODUCTION: We sought to determine the effects of rejection in renal transplant recipients with polyomavirus nephropathy (PVN). METHODS: SCr, biopsy findings, BKV serum and urine loads (Taqman PCR), and BKV antibody titers (HA inhibition assay) were analyzed by two-sample median tests and z tests in 11 patients with median follow-up of 7.3 (2.0 to 31.5) months post-PVN. All patients underwent immunosuppression reduction (ISR) as PVN treatment. RESULTS: Post-PVN, 3 (27%) patients had five rejection episodes, with 80% being mild. Median time to rejection was 18 (2 to 60) weeks. One hundred percent of patients who experienced post-PVN rejection also experienced rejection pre-PVN. Rejection episode treatments consisted of: none in one, increased tacrolimus in two, IVIG in one, IVIG and increased tacrolimus in one. Median viral loads in patients with post-PVN rejection versus those without rejection were not different in serum (2.01 x 10(4) vs 9.00 x 10(4) BKV copies/mL; P = .22) or urine (5.37 x 10(5) vs 8.93 x 10(6) BKV copies/mL; P = .28). Median BKV antibody titers were slightly lower (16384 vs 32768 HA units; P = .02) and median SCr values were significantly higher (2.7 vs 1.9 mg/dL, P = .0003) in patients who had experienced post-PVN rejection. Graft losses occurred in one rejection-free patient (chronic allograft nephropathy) and in one patient who experienced multiple acute rejection episodes, humoral rejection, and worsening PVN. CONCLUSIONS: Patients who experience rejection prior to PVN are at high risk of developing rejection post-ISR and post-PVN; however, low graft loss rates may still be achieved.

Corticosteroid avoidance ameliorates lymphocele formation and wound healing complications associated with sirolimus therapy.

INTRODUCTION: Sirolimus (RAPA) and corticosteroids (CS) both inhibit wound healing. To evaluate the possibility that RAPA and CS have additive effects on wound healing, we evaluated the effects of corticosteroid avoidance (CSAV) on wound healing complications in patients treated with RAPA. METHODS: One hundred nine patients treated with a CSAV regimen (no pretransplantation or posttransplantation CS) were compared with a historical control group (n = 72) that received cyclosporine (CsA), mycophenolate mofetil (MMF), and CS. The CSAV group received low-dose CsA, MMF, RAPA, and thymoglobulin induction. Complications were classified as follows: wound healing complications (WHC) or infectious wound complications (IWC). WHC included lymphocele, hernia, dehiscence, diastasis, and skin edge separation. IWC included wound abscess and empiric antibiotic therapy for wound erythema. RESULTS: The CSAV group was largely CS-free: 11% of patients received CS for rejection, 12% of patients received CS for recurrent disease, and 85% of patients are currently off CS. The CSAV group had a significantly lower incidence of WHC (13.7% vs 28%; P = .03) and lymphoceles (5.5% vs 16%; P = .02) than the control group. There was no difference in the incidence of IWC between the 2 groups. Patients who received CSAV were 18% less likely (P = .57) to develop any type of complication, 41% less likely (P = .20) to develop a WHC, and 71% less likely (P = .018) to develop a lymphocele. CONCLUSIONS: CSAV in a RAPA-based regimen results in a marked reduction in WHC and lymphoceles. Therefore, CSAV provides a promising approach for addressing WHC associated with RAPA therapy.

Histocompatibility testing predicts acute rejection risk in early corticosteroid withdrawal regimens.

UNLABELLED: Histocompatibility testing has been shown to predict acute rejection risk in steroid-based immunosuppression. However, little evidence exists of its ability to predict acute rejection risk in corticosteroid-free patients, with no evidence in early corticosteroid withdrawal (CSWD) under modern immunosuppression. The purpose of this study was to evaluate the ability of histocompatibility testing to identify patients at high risk for acute rejection after early CSWD. METHODS: One hundred eighty-one patients were entered into six IRB-approved early CSWD regimens. Histocompatibility testing included serologic PRA, flow cytometric PRA testing by Class I and Class II MHC beads, and B cell crossmatching with pronase treatment. All rejection episodes were biopsy proven, and grading was assigned using Banff criteria. Influence of individual tests was examined using Chi square univariate and multivariate logistic regression analysis. RESULTS: Median follow-up was 23.5 months (range 7-48 months). Of 181 patients, 16% were repeat transplant recipients, 36% received deceased donor renal transplants, 48% received living related donor renal transplants, and 16% received living unrelated transplants. Overall patient survival was 97%, and death-censored graft survival was 96.5%. Acute rejection rates in the entire follow-up period were 17.7%. 12.4% in primary transplant recipients and 37% in repeat transplant recipients. Multivariate analysis revealed that HLA AB and DR locus mismatching were associated with increased acute rejection risk. Similarly, serologic PRA analysis predicted acute rejection risk; however, flow cytometry crossmatching did not predict acute rejection risk. The greatest single influence on acute rejection risk appeared to be a flow cytometric B cell crossmatch (7.94-fold increased risk). In conclusion, histocompatibility testing can identify patients at high risk for acute rejection following early CSWD. HLA matching, serologic PRA testing, and flow cytometry-based B cell crossmatching can all be used to predict acute rejection risk.

Sequential bone mineral content in small preterm infants with and without fractures and rickets.

Seventy-four infants with birth weights 1009 +/- 28 grams and gestational age 28.6 +/- 0.3 weeks (M +/- SEM) were studied prospectively to test the hypotheses that bone mineral content (BMC) measured by photon absorptiometry, would be: (1) lower in very low birth weight (VLBW) infants with radiographic evidence of fractures and/or rickets (F/R), and (2) will continue to be lower over the first year when compared to VLBW infants without F/R. BMC and bone width (BW) of the distal one-third of left radius and ulna were measured at 5 weeks (n = 8), 14 weeks (n = 61), 26 weeks (n = 58), 40 weeks (n = 59), and 1 year (n = 52). Standardized radiographs of both forearms, and weight, length, and head circumference were also determined at each study age. Investigators and technicians involved in the photon absorptiometry measurements were unaware of the radiographic findings and vice versa. Twenty-three of 74 infants were found to have F/R. BMC of studied infants remained markedly below our previously determined range of "intrauterine bone mineralization," even at 26 weeks after birth. There was no significant difference in BMC or BW between infants with and without F/R, either at the time of confirmation of F/R or during early follow-up; however, BMC was lower at greater than or equal to 6 months and BW was lower at greater than or equal to 9 months in infants with F/R. We suggest that the extremely low BMC measurements in early infancy predispose all VLBW infants to fractures and rickets.

Effect of different vitamin A intakes on very-low-birth-weight infants.

Formula-fed infants with birth weights < or = 1500 g (n = 61) were stratified by 250-g birth-weight ranges and randomly assigned to receive one of three preterm infant formulas (vitamin A contents of 820 IU, 1640 IU, or 2900 IU/MJ; 1 RE = 3.3 IU vitamin A activity) when subjects tolerated 0.314 MJ.kg-1.d-1. Experimental formula feedings were continued until infants weighed approximately 2 kg or until hospital discharge. Vitamin A status as indicated by serum retinol and retinol-binding protein (RBP) concentrations significantly decreased during experimental formula feeding at the lowest vitamin A intake. All subjects fed the formula providing the lowest vitamin A intake had hyporetinolemia (< 0.70 mumol/L, or < 20 micrograms/dL), which occurred less frequently (P < 0.05) with the intermediate (6 of 20) and the high (6 of 21) vitamin A intakes. Other outcome measures, including increases in weight, length, and head circumference, and ventilatory support and oxygen therapy, were not different among groups. After the end of the experimental formula-feeding period, all infants were fed standard infant formulas with a vitamin A content of 715 IU/MJ. In a subset of 19 of these infants, subsequent vitamin A status was monitored at ages 6-12 mo and was found to be comparable with that of older children and adults, regardless of the vitamin A content of the formula fed during hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Lead exposure and the motor developmental status of urban six-year-old children in the Cincinnati Prospective Study.

The relationship between asymptomatic lead exposure and subtle deficits in intellectual attainment has been relatively well established by modern studies. However, neuromotor performance has rarely been the focus of these investigations. It was postulated that motor developmental outcomes may be more sensitive indicators of lead's adverse effects on the central nervous system as they are probably less confounded with social factors than cognitive and academic outcomes. A comprehensive neuromotor assessment battery was administered to 245 six-year-old urban inner-city children enrolled in the Cincinnati Lead Study. These children have been followed since birth with quarterly assessments of blood lead concentrations, medical status, and neurobehavioral development. Prior to covariate adjustment, neonatal, but not prenatal blood lead levels were associated with poorer scores on assessments of bilateral coordination, upper-limb speed and dexterity, and a composite index of fine-motor coordination. Averaged postnatal blood lead levels were also associated with lower scores on the aforementioned subtests as well as a measure of visual-motor control. Following statistical adjustment for covariates, neonatal blood lead levels were associated with poorer performance on a measure of upper-limb speed and dexterity and the fine-motor composite. Postnatal blood lead levels remained significantly associated with poorer scores on measures of bilateral coordination, visual-motor control, upper-limb speed and dexterity, and the fine-motor composite. Low to moderate lead exposure is associated with moderate deficits in gross and especially fine-motor developmental status. Results of this study provide support for recent initiatives to reduce the exposure of children to sources of environmental lead.

Sequential serum aluminum and urine aluminum: creatinine ratio and tissue aluminum loading in infants with fractures/rickets.

Aluminum toxicity is associated with the development of bone disorders, including fractures, osteopenia, and osteomalacia. Fifty-one infants with a mean (+/- SEM) birth weight of 1007 +/- 34 g, gestational age of 28.5 +/- 0.3 weeks, and serial radiographic documentation at 3, 6, 9, and 12 months for the presence (n = 16) or absence (n = 35) of fractures and/or rickets were studied at the same intervals to determine the serial changes in serum aluminum concentrations and urine aluminum-creatinine ratios. Autopsy bone samples were used to determine the presence of tissue aluminum. Serum aluminum concentrations from 46 infants were stable and similar between groups, with mean values between 15 and 22 micrograms/L. Urine aluminum-creatinine (micrograms per milligram) ratios from 14 infants were higher in infants with fractures and/or rickets (0.26 +/- 0.06 vs 0.12 +/- 0.04) at onset, and rate of decrease in aluminum-creatinine ratio was faster in infants without fractures and/or rickets. All but three infants were tolerating complete enteral feeding at all sampling points. One infant who received aluminum-containing antacid had marked increase in serum aluminum to 83 micrograms/L while urine aluminum-creatinine ratio increased from 0.09 to a peak of 8.53. Vertebrae from three infants at autopsy (full enteral feeding was tolerated for 37 and 41 days in two infants, respectively) showed aluminum deposition in the zone of provisional calcification and along the newly formed trabecula.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal and infant lead exposure: effects on growth in stature.

The growth of a cohort of 260 infants was prospectively followed up from birth. Blood lead and stature measurements were obtained every 3 months until 15 months of age. Fetal lead exposure was indexed by measuring lead in maternal blood during pregnancy. A longitudinal analysis revealed that covariate adjusted growth rates in stature were negatively related to the infants' postnatal blood lead concentration, as indexed by increase in average blood lead values from 3 to 15 months. However, this relationship between growth rate and change in blood lead concentration was evidenced only among those infants whose mothers had prenatal blood lead levels greater than the maternal cohort median of 7.7 micrograms/dL is about 2 cm shorter at 15 months of age if, postnatally, the infant incurred a 10-micrograms/dL blood lead increase during the 3- to 15-month interval of life, compared with an infant who has no increase.

Serum vitamin D metabolites and bone mineralization in young children with chronic low to moderate lead exposure.

One hundred five children (49 male, 99 black) with known lead exposure indices from birth and adequate nutrient intake of calcium, phosphorus, and vitamin D were studied at 1 of 3 ages (21, 27, or 33 months) to determine the effects of chronic low to moderate lead exposure on circulating concentrations of vitamin D metabolites and bone mineral content as determined by photon absorptiometry. Univariate multiple regression analyses showed no direct relationship of blood lead levels to vitamin D metabolites or bone mineral content. Structural equation analyses which took into account potential covariates of age, season, race, and sex showed estimated declines in serum concentrations of total calcium (from 9.72 to 9.61 mg/dL), phosphorus (from 5.4 to 4.67 mg/dL), and 25-hydroxyvitamin D (from 27.24 to 25.8 ng/mL) and estimated increases in concentrations of parathyroid hormones (from 73.03 to 83.14 microL Eq/mL), 1,25-dihydroxyvitamin D (from 62.39 to 62.69 pg/mL), and bone mineral content (from 222.66 to 234.91 mg/cm) over the observed range of average lifetime blood lead concentrations (4.76 to 23.61 micrograms/dL, geometric mean 9.74 micrograms/dL). However, the only statistically significant effect of average lifetime blood lead concentration was that for phosphorus, and the multivariate test of the combined effects of lead on these six outcomes was not statistically significant (P = .2). It is concluded that significant alterations in vitamin D metabolism, calcium and phosphorus homeostasis, and bone mineral content are not present in children whose nutritional status is adequate and who experience low to moderate lead exposure.

Contribution of social and developmental factors to lead exposure during the first year of life.

The social and developmental correlates of early lead exposure were explored in an interim analysis of data from an ongoing longitudinal investigation in Cincinnati. Regardless of the apparent net availability of lead in the infant's physical environment, parental behavior was still significantly associated with infant blood lead levels. However, this was only the case after infants in the study reached 6 months of age and beyond when prewalking progression and early walking made parental management all the more critical. Future lead screening and abatement programs should include supports for the caretaker-child relationship.

Low-level fetal lead exposure effect on neurobehavioral development in early infancy.

A prospective method was used in this study to assess the effects of fetal lead exposure on neurodevelopmental status in 3- and 6-month old infants. At their first prenatal medical appointments, 305 lower socioeconomic status women residing in predesignated lead-hazardous areas of Cincinnati were recruited. Lead was measured in whole blood in both the mother and fetal-placental unit (prenatal and cord) and the neonate (ten days and 3 months). All blood lead levels were less than 30 micrograms/dL. Infant development was assessed with the Bayley scales at 3 and 6 months of age. Multiple regression analyses which treated perinatal health factors such as birth weight and gestation as confounders indicated an independent, inverse relationship between both prenatal and neonatal blood lead levels and performance on the Bayley Mental Developmental Index at both ages. Male infants and infants from the poorest families appeared to be especially sensitive to these psychoteratogenic influences. Further study using a structural equations approach indicated that neurobehavioral deficits were partly mediated by lead-related reductions in birth weight and gestation.

Structural equation modeling in environmental risk assessment.

Environmental epidemiology requires effective models that take individual observations of environmental factors and connect them into meaningful patterns. Single-factor relationships have given way to multivariable analyses; simple additive models have been augmented by multiplicative (logistic) models. Each of these steps has produced greater enlightenment and understanding. Models that allow for factors causing outputs that can affect later outputs with putative causation working at several different time points (e.g., linkage) are not commonly used in the environmental literature. Structural equation models are a class of covariance structure models that have been used extensively in economics/business and social science but are still little used in the realm of biostatistics. Path analysis in genetic studies is one simplified form of this class of models. We have been using these models in a study of the health and development of infants who have been exposed to lead in utero and in the postnatal home environment. These models require as input the directionality of the relationship and then produce fitted models for multiple inputs causing each factor and the opportunity to have outputs serve as input variables into the next phase of the simultaneously fitted model. Some examples of these models from our research are presented to increase familiarity with this class of models. Use of these models can provide insight into the effect of changing an environmental factor when assessing risk. The usual cautions concerning believing a model, believing causation has been proven, and the assumptions that are required for each model are operative.

An empirical comparison of lead exposure pathway models.

Structural equation modeling is a statistical method for partitioning the variance in a set of interrelated multivariate outcomes into that which is due to direct, indirect, and covariate (exogenous) effects. Despite this model's flexibility to handle different experimental designs, postulation of a causal chain among the endogenous variables and the points of influence of the covariates is required. This has motivated the researchers at the University of Cincinnati Department of Environmental Health to be guided by a theoretical model for movement of lead from distal sources (exterior soil or dust and paint lead) to proximal sources (interior dust lead) and then finally to biologic outcomes (handwipe and blood lead). The question of whether a single structural equation model built from proximity arguments can be applied to diverse populations observed in different communities with varying lead amounts, sources, and bioavailabilities is addressed in this article. This reanalysis involved data from 1855 children less than 72 months of age enrolled in 11 studies performed over approximately 15 years. Data from children residing near former ore-processing sites were included in this reanalysis. A single model adequately fit the data from these 11 studies; however, the model needs to be flexible to include pathways that are not frequently observed. As expected, the more proximal sources of interior dust lead and handwipe lead were the most important predictors of blood lead; soil lead often had a number of indirect influences. A limited number of covariates were also isolated as usually affecting the endogenous lead variables. The blood lead levels surveyed at the ore-processing sites were comparable to and actually somewhat lower than those reported in the the Third National Health and Nutrition Examination Survey. Lessened bioavailability of the lead at certain of these sites is a probable reason for this finding.

Lead exposure and neurobehavioral development in later infancy.

A prospective methodology was used to assess the neurobehavioral effects of fetal and postnatal lead exposure during the first 2 years of life. Lead was measured in whole blood prenatally in mothers and at quarterly intervals in the infant. Prenatal blood lead levels were low (mean = 8.0 micrograms/dL). However, approximately 25% of the study infants had at least one serial blood lead level of 25 micrograms/dL or higher during the second year of life. Multiple regression and structural equation analyses revealed statistically significant relationships between prenatal and neonatal blood lead level and 3- and 6-month Bayley Mental and/or Psychomotor Development Index. However, by 2 years of age, no statistically significant effects of prenatal or postnatal lead exposure on neurobehavioral development could be detected. Data consistent with the hypothesis that a postnatal neurobehavioral growth catch-up occurred in infants exposed fetally to higher levels of lead are presented.